Physical activity and nicotine dependence among a national sample of young U.S. adults who smoke daily: Evaluation of cross-sectional and longitudinal associations to determine which behavior drives this relationship

•Research suggests a bidirectional relationship between physical activity and smoking.•Little research has examined the association between physical activity and nicotine dependence.•No study has concurrently examined the cross-sectional and prospective associations between physical activity and nicotine dependence or smoking.•When examined prospectively, nicotine dependence influenced physical activity, but there was no evidence of the reverse pathway.•Nicotine dependence drives the physical activity-nicotine dependence relationship.

The association between nicotine dependence and physical activity (PA) is relatively unknown. No study has concurrently examined the cross-sectional and longitudinal associations between PA and nicotine dependence, which was the primary purpose of this study. A secondary purpose was to examine how well nicotine dependence and PA behavior track over a two-year period. Data from the 2003–2005 National Youth Smoking Cessation Survey (NYSCS) were used, with young adults (18–24 yrs; n = 1168) being followed over a two-year period. Physical activity was assessed using a questionnaire and nicotine dependence was assessed using the modified Fagerstrom Test for Nicotine Dependence scale. This study identified three notable findings: 1) baseline PA and nicotine dependence demonstrated a bidirectional, cross-sectional association (e.g., β = − 0.23; 95% CI: − 0.44 to − 0.02; p = 0.02); 2) when examined longitudinally, nicotine dependence influenced PA (OR = 0.90; 95% CI: 0.82–0.99; p = 0.04), but there was no evidence of the reverse pathway (i.e., PA influencing 2-year follow-up smoking status [OR = 0.95; 95% CI: 0.66–1.39; p = 0.82) or nicotine dependence (β = 0.05; 95% CI: − 0.14 to 0.24, p = 0.61]); and 3) both PA (OR = 3.52, 95% CI: 2.68–4.69; p < 0.001) and nicotine dependence (β = 0.52; 95% CI: 0.46–0.58, p < 0.001) tracked relatively well over a two-year period during early adulthood. These findings suggest that both behaviors (physical activity and nicotine dependence) track over time, but nicotine dependence appears to be driving the cross-sectional relationship between nicotine dependence and physical activity, as opposed to the reverse pathway.